PTL 1 discloses a method using azo pigments as a toner colorant. When using such azo pigments as a toner colorant, it is necessary to finely disperse the pigments in a binder resin or a polymerizable monomer of a toner in order to increase the spectrum characteristics, such as coloring power and transparency.
However, when the pigments are finely dispersed in order to increase the spectral characteristics, such as coloring power and transparency, of the pigments, the growth, transition, and the like of crystals are likely to occur due to the heat history or the contact with a solvent in a dispersion process and subsequent manufacturing processes, which causes problems of a reduction in coloring power and transparency and the like.
In order to improve the dispersibility of the pigments, various pigment compositions and pigment dispersants constituting the same have been proposed. PTL 2 discloses an example of using a comb type polymer dispersant having an acid or basic portion known as Solsperse (Registered Trademark). Furthermore, PTL 3 discloses a polymer dispersant in which a portion having affinity with the azo pigment which is a colorant and an oligomer or a polymer portion having affinity with a solvent and a binder resin are bonded through a covalent bond.